This is often used for muscle biopsies. The stain consists of chromotrope 2R and Fast Green. It is often counterstained with hematoxylin to show muclei. Proteinacious structures such as muscle fibers and collagen fibers show up as green, nuclei show up as purple, and lipophillic, membranous structures such as mitochondria, T-tubules and sarcoplasmic bodies show up in red. It can show an increase in mitochondria (certain diseases of muscle). It may also help to identify an increase in collagenous connective tissue fibers, or to differentiate between collagen and smooth muscle fibers.